My kids are in the habit of using a new glass every time they get a drink of water. As a result, the top rack of our dishwasher fills up much faster than the bottom rack.
I bought a set of 13 squishy rubber Creepy Creatures suction-cup glass markers ($(removed)) so everyone in the family can claim a water glass for the day. These markers were meant for halloween party wineglasses, but they stick to water glasses any time of the years.
We keep them on the tile backsplash under the glass cabinet.